In this paper, thermodynamic phase behaviour, implications, and strategies for the CO2 storage process in the fractured tight/shale reservoirs (i.e., nanoproes) with adsorptions are studied. First, an analytical equation of state is modified to calculate the nanoscale phase behaviour by considering the effects of pore radius and molecule–molecule interactions. Second, a new empirical correlation for calculating the adsorption thickness in nanopores is initially developed. The modified equation of state coupled with the new adsorption thickness correlation and fracture geometry equation is used to calculate the phase behaviour of confined pure and mixing CO2 streams in fractured nanopores with adsorptions. Third, the pressure–volume diagrams, pressure–temperature diagrams, and critical properties of 12 pure substances of CO2, N2, and alkanes of C1–10 and 12 binary and ternary CO2-dominated mixtures are studied. The calculated pressures for all cases in nanopores with and without the adsorptions and fractures are reduced with the system volume increases but increased by increasing the system temperature with constant compositions. The pressures in nanopores are always larger than those in bulk phase at small volumes but in good agreement at large volumes. In comparison with the N2 or C1–10, the pure CO2 is more easily transited to be a liquid or supercritical phase. Any additions of contaminations (e.g., N2 or C1–10) into the pure CO2 increase the pressures in the pressure–volume or temperature diagram while decrease the critical properties to different extent, especially in nanopores, wherein the N2 exerts the strongest effect and the effects of the alkanes are weakened with the carbon number increase. Overall, three optimum strategies are determined for CO2 storage projects in the deep tight/shale formations as follows: large pore radii, purified CO2 streams, and low temperatures.
Titanate nanotubes (TNTs) have been reported to show good adsorption performance for heavy metals, but researches on organic contaminants adsorption by TNTs are limited. In this study, co-adsorption of a heavy metal (Cu) and an emerging organic contaminant (ciprofloxacin, CIP) by TNTs was investigated in binary systems. TNTs could simultaneously remove the two contaminants, with a high adsorption capacity of 234.5 μmol/g for Cu(II) and 237.0 μmol/g for CIP at pH 4 in the binary system. pH greatly affected adsorption due to speciation variation of the contaminants and surface charge change of TNTs. Cu(II)-CIP complexes dominated adsorption capacity and mechanism. Adsorption of CIP was promoted by high concentration of Cu(II) at pH 3–8 due to formation of abundant Cu(CIP±)2+, while inhibited by low concentration of Cu(II) because of competitive adsorption. The adsorption affinity of CIP species to TNTs was ranked as: Cu(CIP±)2+ > CIP+ > CIP± > Cu(CIP±)2+ > Cu(CIP−·CIP±)+ > CIP−. In comparison, the co-existence of CIP slightly affected Cu(II) adsorption considering the strong affinity of Cu2+ to TNTs. X-ray photoelectron spectrometer (XPS) and Fourier transform infrared spectroscopy (FTIR) results further confirmed the formation of Cu(II)-CIP complexes through –NH2Cu/–COOCu linkages. This work not only proposed a feasible technology for co-removal of heavy metals and organics from water, but also presented insight into interaction mechanisms of different contaminants with nanomaterials during adsorption.
This paper investigates an optimal scheduling method for the operation of combined cycle gas turbines (CCGT). The objective is to minimize the CO2 emissions while supplying both electrical and thermal loads. The paper adopts a detailed model of the units in order to relate the heat and power outputs. The grid constraints as well as system losses are considered for both the electrical and thermal systems. Finally, the optimal power dispatch lies on the hybridization of a Mixed Integer Linear Programing (MILP) scheduling with a greedy search method. Different sets of simulations are run for a small 5-bus test case and a larger model of Jurong Island in Singapore. Several load levels are considered for the heat demand and the impact of the steam pipe capacities is highlighted.
Global livestock husbandry provides ecosystem goods and services but also emits 7.1 Gt CO2-eq. of greenhouse gases (GHGs) per year. To lower GHG emissions intensity, appropriate production management systems should be identified. Since the 1980s, grassland livestock husbandry in China has transformed gradually from pastoralism into individual household management under the Grassland Household Contract System Policy. However, little is known about how this transition influences GHG emissions. We selected two case study sites representing two different forms of rangeland management systems in Ruoergai county of the Qinghai-Tibet Plateau, viz. 1) household-based all year continuous grazing under the individual use of rangeland with fences demarcating boundaries; 2) community-based seasonal grazing under the common use of the whole rangeland. The objective was to examine the differences in greenhouse gas emission intensity between the two systems using life cycle assessment (LCA). The results showed that the transition from community-based seasonal grazing into household-based continuous grazing increased the GHG emissions intensity from -0.62 kgCO2-eq/kg meat to 10.51 kgCO2-eq/kg meat. The increase was primarily attributed to changes in soil carbon storage. Findings suggest that to minimize GHG emissions and environmental degradation, community-based seasonal grazing in the pastoral area of Qinghai-Tibet Plateau should be maintained. Enhancing soil carbon sequestration by adopting appropriate practices would further reduce the GHG emissions intensity arising from the livestock system.
In this letter, a distributed network model describing the effects of the border traps and distributed channel resistance on the impedance frequency dispersion of lateral MOS devices is proposed. The proposed model is verified using a gate recessed, normally-off Al2O3/GaN MOSFET structure operating as a MOS diode. The measured frequency-dependent capacitance and conductance curves of the MOS diode over a wide frequency range are found to be in good agreement with the proposed model. According to the intrinsic property of border traps to the ac signal, the proposed model is further modified to get the spatial distribution of border traps. The new insight derived from the impedance dispersion characteristics of lateral MOS devices is critical for quantitative analysis of the quality of III-V lateral MOS structures.
BACKGROUND: A 'mortality risk score' (MS) based on ten prominent mortality-related cytosine-phosphate-guanine (CpG) sites was previously associated with all-cause mortality, but has not been verified externally. We aimed to validate the association of MS with mortality and to compare MS with three aging biomarkers: telomere length (TL), DNA methylation age (DNAmAge) and phenotypic age (DNAmPhenoAge) to explore whether MS can serve as a reliable measure of biological aging and mortality. METHODS: Among 534 males aged 55-85 years from the US Normative Aging Study, the MS, DNAmAge and DNAmPhenoAge were derived from blood DNA methylation profiles from the Illumina HumanMethylation450 BeadChip, and TL was measured by quantitative real-time polymerase chain reaction (qRT-PCR). RESULTS: A total of 147 participants died during a median follow-up of 9.4 years. The MS showed strong associations with all-cause, cardiovascular disease (CVD) and cancer mortality. After controlling for all potential covariates, participants with high MS (>5 CpG sites with aberrant methylation) had almost 4-fold all-cause mortality (hazard ratio: 3.84, 95% confidence interval: 1.92-7.67) compared with participants with a low MS (0-1 CpG site with aberrant methylation). Similar patterns were observed with respect to CVD and cancer mortality. MS was associated with TL and DNAmPhenoAge acceleration but not with DNAmAge acceleration. Although the MS and DNAmPhenoAge acceleration were independently associated with all-cause mortality, the former exhibited a higher predictive accuracy of mortality than the latter. CONCLUSIONS: MS has the potential to be a prominent predictor of mortality that could enhance survival prediction in clinical settings.
As nitrous acid (HONO) photolysis is an important source of hydroxyl radical (OH), apportionment of the ambient HONO sources is necessary to better understand atmospheric oxidation. Based on the data HONO-related species and various parameters measured during the one–month campaign at Wangdu (a rural site in North China plain) in summer 2014, a box model was adopted with input of current literature parametrizations for various HONO sources (nitrogen dioxide heterogeneous conversion, photoenhanced conversion, photolysis of adsorbed nitric acid and particulate nitrate, acid displacement, and soil emission) to reveal the relative importance of each source at the rural site. The simulation results reproduced the observed HONO production rates during noontime in general but with large uncertainty from both the production and destruction terms. NO2 photoenhanced conversion and photolysis of particulate nitrate were found to be the two major mechanisms with large potential of HONO formation but the associated uncertainty may reduce their importance to be nearly negligible. Soil nitrite was found to be an important HONO source during fertilization periods, accounted for (80 ± 6)% of simulation HONO during noontime. For some episodes of the biomass burning, only the NO2 heterogeneous conversion to HONO was promoted significantly. In summary, the study of the HONO budget is still far from closed, which would require a significant effort on both the accurate measurement of HONO and the determination of related kinetic parameters for its production pathways.
